Show Unnecessary "0" inputs

Question

I am building a calculator and have run into a problem with displaying unnecessary 0's (it isn't displaying them and I want it to be).

An example of what it does now is as follows. [Represents Calculator Screen]

[Blank Calculator Screen]

User hits "4"

[4]

User hits "."

[4]

User hits "0"

[4]

User hits "0"

[4]

User hits "5"

[4.005]

Instead, I want to make it do the following:

[Blank Calculator Screen]

User hits "4"

[4]

User hits "."

[4.]

User hits "0"

[4.0]

User hits "0"

[4.00]

User hits "5"

[4.005]

I use a number formatter as shown below...

 formatter = [[NSNumberFormatter alloc] init];
     formatter.numberStyle = NSNumberFormatterDecimalStyle;
     formatter.maximumIntegerDigits = 13;
     formatter.minimumFractionDigits = 0;
     formatter.maximumFractionDigits = 13;
     formatter.maximumSignificantDigits = 13;
     formatter.usesGroupingSeparator = YES;
     formatter.groupingSeparator = @",";
     formatter.decimalSeparator = @".";
     formatter.generatesDecimalNumbers = true;

I use the following to call my numbers...

 buttonScreen.text = [formatter stringFromNumber:
 [NSNumber numberWithDouble:currentNumber]]

Thanks!

Answer 1

It's not giving you the zeroes because 4 is the exact floating point representation of 4, 4.0, 4.00, etc. I suggest that you store the user input into a NSString *, which you then convert into an NSNumber when you need to do actual math.

Answer 2

You could get around this issue by not evaluating the input before "=" or an operation key is pressed.

You would just add to the string and transform the string into the correct number once the entry is finished which you know because a different key has been pressed.